You can wear something loose fitting on the bottom (so long as you have something to tie around your hips) but it's a better idea to wear something form fitting on top and on bottom (not necessarily tight). Wearing something form fitting allows you to see what your body is doing easier. Also, there is no need to show your belly, just don't wear a big t-shirt or anything. Once again, form fitting makes it easier to see what's going on. No need for a coin scarf either. As long as you have a simple scarf to tie around your hips it'll be fine!!!

For class I wear a unitard that has a mesh midsection, and a hip scarf with no coins. You could wear a leotard and tights if you have them and are used to dance classes. You could wear a leotard and a broomstick skirt and a hipscarf if you need to feel more covered. You are going to be spending a lot of time looking at yourself in the mirror, so pull up your hair (in case you get sweaty) and wear some lip gloss and sparkly earrings if you have them.

I would suggest wearing pants, so that your instructor can easily see what your legs are doing (or not, as the case may be ). Yoga pants or leggings are excellent for this. And as ejaghana mentioned, wearing a big boxy t-shirt or sweatshirt also makes it difficult for the instructor to see what's going on under there. I would wear as close fitting garments as you feel comfortable in.

I am actually loving the hot weather because a lot of my students are showing up for class in shorts. I can spot a hyperextended knee a mile away these days! ..l;,

Top: form fitting T shirt or top - nothing too loose or too big.
A leotard is perfect, it shows your torso, and in case you are figure concious it actually slims down your waist as well. The main bonus is that you don't have to keep tugging your shirt, or pulling it down.
You also do not need to bare your midriff.

bottom: I would suggest pants or shorts.
Definitely no skirt. Your teacher needs to see your feet (to make sure they are not turned out when they need to be parallel) and your knees - it's very important.
Yoga pants are perfect. Make sure your pants sit on your hips, and not your waist.
Also no jeans, because you may be sweating, and hopefully at the end you'll be doing streches, and those could be uncomfortable in jeans.

Hipscarves are helpful for beginners, it helps them get "into the mood" :))

I am actually loving the hot weather because a lot of my students are showing up for class in shorts. I can spot a hyperextended knee a mile away these days!

I'm actually getting quite good at spotting them in practically any pant. Except big harems. Sometimes you can tell, but it's really luck of the draw.

I'm another who prefers stretchy pants of some kind rather than a skirt. Sweat pants or leggings are fine, plus a t-shirt or, if you're confident showing your midsection, a crop top. A good supportive bra is a must, even if you don't wear one normally - you're going to want that support!

Anne, I'd call the instructor or studio/community center regarding the type of flooring in the classroom before I went barefoot. The room where I teach has a nice wooden floor -- but it's unfinished and for years the room has also been the room where the tap classes are held. That means the floor is 1) dirty and full of metallic tap dust constantly and 2) sometimes a bit rough, and some gals who refuse to wear shoes have picked up the occasional splinter. I advise all my students not to go barefoot (and from the former sentence you can tell about how well they listen to me..c:: ). I'd recommend Hermes sandals, Grecian sandals, character shoes, jazz oxfords (all styles of dance shoes available from dance vendors online -- try Danny's Discount Dance or just Google Capezio . . )

For me, I usually wear spandex shorts and a tank top. I don't wear a hip scarf as I find the weight of the fabric and coins distracting. I also find the extra movement is causes distracting. I can see much better my execution of the steps without a scarf. But every person is different and since you are new you may want to wear the scarf so that you can see your hip work and your isolations. You may want to wear dance shoes depending on the surface of the floor. The surfaces I work on enable me to practice barefoot.